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Backwards Planning Approach for Rapid Attitude Maneuvers epubs. · PDF file Backwards Planning Control in the 3D attitude space are proposed here. The methods refer both for the first

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  • Backwards Planning Approach for Rapid

    Attitude Maneuvers Steering Dov Verbin

    Submitted for the Degree of

    Doctor of Philosophy

    from the

    University of Surrey

    UNIVERSITY OF

    Surrey Space Centre

    Faculty of Electronics and Physical Sciences

    University of Surrey

    Guildford, Surrey, GU2 7XH, U.K.

    March 2012

    © Dov Verbin 2012

  • ProQ uest Number: U606525

    All rights reserved

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  • Abstract

    Remote sensing satellites are often built with payloads that do not include hue of sight steering mechanisms, such that pointing their payloads requires rotation of the whole satellite. In cases, when frequent line of sight retargeting is required, there is a need for efficient actuators and control schemes that would support rapid attitude maneuvering together with adequate pointing accuracy and stability between the maneuvers. These control schemes shall accommodate a variety of realistic conditions, such as general three dimensional maneuver direction, existence of initial and/or final angular rates, non zero net angular momentum and various actuators constraints.

    Within this frame, this research develops the Backwards Planning approach as one of the possible control methods for rapid maneuvering. The method is based on state feedback and combines time efficiency together with straight forward computation flow. Novel efficient methods to execute the Backwards Planning Control in the 3D attitude space are proposed here. The methods refer both for the first saturated control phase of the maneuver and for the last braking phase.

    The actuators used for the spacecraft control in this research are either Reaction Wheels (RWs) or Single Gimbal Control Moment Gyros (SGCMGs) or both of them together. The advantage of the SGCMG is in rapid rotational maneuvering, but their application for high quality pointing requires very accurate gimbal mechanisms. On the other hand, RWs are usually more suitable for accurate pointing, but their torque to power performance is inferior in maneuvering. It is shown that the coordination of SGCMGs and RWs together enables to draw more performance from the SGCMGs in terms of agility and meet the pointing requirements between maneuvers where only the RWs are used.

    Novel SGCMG steering laws are suggested as well. While the steering laws determine the required angular rate for each gimbal, most steering laws are defined in the angular momentum domain and output the gimbals angular rates to produce a given required torque or angular momentum increment. This research however, practices a novel steering law in the gimbal angles domain. While both steering laws turn to be dynamically equivalent for small control signals, as in the steady state, it is shown that the steering in the gimbal angles domain is more effective in maneuvering with the Backwards Planning control logic.

    Backwards Planning Approach for Rapid I Verbin Attitude Maneuvers Steering

  • Acknowledgements

    I would like to thank my supervisors, Prof. Vaios Lappas and Prof. Sir Martin Sweeting for encouraging me in taking this effort and supporting me all the way through.

    I would hke to thank Mr. Moshe Shachar from Israel for his support and human relations assistance that enabled to start this research.

    Many thanks as well to my wife Shula and my colleagues in lAI, Mr. Dan Israeli and Mr. Dan Erenthal for their support and good advices.

    Backwards Planning Approach for Rapid - Verbin Attitude Maneuvers Steering

  • Contents 1 I n tr o d u c t io n ............................................................................................................. 1

    1.1 Overview.......................................................................................................................... 1 1.2 Problem Statement.......................................................................................................... 2 1.3 Aims................................................................................................................................. 3 1.4 Objectives.........................................................................................................................4 1.5 Research Novelties..........................................................................................................4 1.6 Publications......................................................................................................................6 1.7 Thesis Outline..................................................................................................................7

    2 B a c k g r o u n d ..............................................................................................................8 2.1 Single Axis Time Optimal Rotation................................................................................8 2.2 Maneuver Boundary Conditions...................................................................................10 2.3 The 3D Rotation Equations........................................................................................... 16

    3 L ite r a tu r e R e v ie w ..............................................................................................22 3.1 Time Optimal 3D Maneuvering................................................................................... 22 3.2 Attitude Regulation and Tracking................................................................................ 24 3.3 Near Time Optimal Methods....................................................................................... 26 3.4 Reaction Wheels Control..............................................................................................28 3.5 SGCMG Steering Laws and Control Structure ...............................................29 3.6 The Hybrid Configuration that Includes RWs and SGCMGs..................................... 30 3.7 This Thesis in the Context of the Literature............................. 31

    4 R e a c t io n W h e e l c o n tr o l ....................................... 33 4.1 Control Capability Modeling........................................................................................33 4.2 The Control Law........................................................................................................... 47 4.3 Simulation Results........................................................................................................56

    5 S G C M G C o n tr o l................................................................................................ 65 5.1 Control Capability and Allocation............................................................................... 65 5.2 Ideal Case Control.........................................................................................................75 5.3 Ideal Case Simulation Results...................................................................................... 81 5.4 Realistic Case Control...................................................................................................86 5.5 Realistic Case Control Simulation Tests ...........................................................89

    6 H y b r id A c tu a to r s C o n tr o l ............................................................................ 99 6.1 The Hybrid Control Concept........................................................................................ 99 6.2 Hybrid Control Simulation Tests................................................................................105 6.3 Qualitative Considerations in Choosing a Hybrid System.........................................112

    7 C o n c lu s io n s ..........................................................................................................115 7.1 Summary......................................................................................................................115 7.2 Novelty........................................................................................................................ 117 7.3 Future Work................................................................................................................ 121

    References.............................................................................................................................. 122

    Backwards Planning Approach for Rapid ••• r . Vprhin Attitude Maneuvers Steering

  • List of Figures

    2-1 Satellite - Target geometry .................................................................................................... 13

    2-2 A general braking curve stmcture................................................................................................... 28

    2-3 Common Braking Curve control structure with RW or SGCMG.................................................. 30

    4-1 Typical Reaction Wheel envelope of operation.......................................................

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